Abstract

Long-chain fatty acids are the preferred substrate of cardiac muscle. Therefore, radiolabeled free fatty acids are a natural choice for the non- invasive evaluation of myocardial metabolism and extensive research has focused on the development of radiolabeled free fatty acids for myocardial imaging (1–5). Evans et al. in 1965 successfully radioiodinated (I–131) oleic acid across a double bond and produced crude images of the myocardium in dogs, thus demonstrating the potential of radiolabeled free fatty acids for external, noninvasive myocardial imaging (1). Subsequently, heptadecanoic acid and hexadecanoic acid have been studied extensively in experimental animals and have shown promise in preliminary clinical assessments (2–5). However, for myocardial imaging, the terminally iodinated straight-chain free-fatty acids have two major problems, including (a) they are metabolized rapidly by the myocardium and (b) significant blood pool radioactivity results from free iodide released along with beta oxidation of the fatty acid in the myocardium and liver.